A technique to lessen the risk of loss of data includes adopting a redundancy policy that provides periodic back up of data stored on a primary data storage device to a backup storage device for safe-keeping. If the data that is to be backed up is regularly copied to the backup storage device, a recent copy of the data may be restored in the event the data is lost from the primary storage device. When performing data backup, one of the key questions is “What data should be backed up?” In many systems, this involves considering each file that is in the scope of the information that is to be backed up and making a decision as to whether or not it needs to be backed up. That is, determine whether a back-up copy for the data already exists. As file systems get larger, the backup process may take a long time, as each file needs to be accessed to at least extract metadata as to the last time it was modified, and this often results in a higher load that may make the system unresponsive.